Nanolithography methods and products therefor and produced thereby

ABSTRACT

In one aspect, a method of nanolithography is provided, the method comprising providing a substrate; providing a scanning probe microscope tip; coating the tip with a deposition compound; and subjecting said coated tip to a driving force to deliver said deposition compound to said substrate so as to produce a desired pattern. Another aspect of the invention provides a tip for use in nanolithography having an internal cavity and an aperture restricting movement of a deposition compound from the tip to the substrate. The rate and extent of movement of the deposition compound through the aperture is controlled by a driving force.

This application is a continuation of Ser. No. 11/100,483, filed Apr. 7,2005, which is a continuation of Ser. No. 10/059,593, filed Jan. 28,2002, now abandoned, which is a continuation-in-part of Ser. No.09/477,997, filed Jan. 5, 2000, now U.S. Pat. No. 6,635,311 B1; andwherein Ser. No. 10/059,593, filed Jan. 28, 2002 also claims benefit ofSer. No. 60/264,550, filed Jan. 26, 2001, the complete disclosures ofwhich are all incorporated herein by reference.

This invention was made with government support under grant no.F49620-96-1-0155 from the Air Force Office of Science and Research. TheU.S. government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates to methods of nanolithography and productstherefor and produced thereby.

BACKGROUND OF THE INVENTION

Lithographic methods are at the heart of modern day microfabrication,nanotechnology and molecular electronics. Microfabrication techniquessuch as photolithography, microcontact printing, micromachining, andmicrowriting can produce patterns as small as 100 nm, but the productionof sub-100 nm structures still poses a challenge. Amro et al., Langmuir,16, 3006-3009 (2000). At present, such high-resolution fabrication canbe achieved using lithography techniques and a variety of scanning probelithography (SPL) techniques have been developed for this purpose.

One such technique is dip pen nanolithograpy (DPN). See, e.g., Piner etal., Science, 283, 661-663 (1999); Hong et al., Science, 286, 523-528(1999); Weinberger et al., Advanced Materials, 12, 1600-1603 (2000); andPCT application WO 00/41213. DPN is a nanolithography technique by whichmolecules are directly transported to a substrate of interest in apositive printing mode. DPN utilizes a solid substrate as the “paper”and a scanning probe microscope (SPM) tip (e.g., an atomic forcemicroscope (AFM) tip or a near field scanning optical microscope (NSOM)tip) as the “pen.” The tip is coated with a patterning compound (the“ink”), and the coated tip is used to apply the patterning compound tothe substrate to produce a desired pattern. DPN enjoys numerousadvantages for depositing “nanoscale” wide mono- or multilayermolecules. The DPN delivery mechanism may involve the formation of ameniscus around the SPM tip and the control of the movement of thepatterning molecules to the surfaces on which they are deposited by adriving force. Considerable recent work done in this area demonstratesthe efficacy of the DPN approach to pattern monolayer molecules at thelateral width which is limited only by the liquid meniscus. DPN isdescribed in pending application Ser. No. 09/477,997, filed Jan. 5,2000, the complete disclosure of which is incorporated herein byreference.

Problems that arise with DPN technology stem from the dependence of thetechnique on the liquid meniscus. For example, the lateral width of theline written by the “pen” using DPN technology is limited by the widthof the meniscus formed. The meniscus is subject to variations in therelative humidity as well as chemical interactions between the solventand the substrate. The size of the meniscus also affects the rate of thetransport of the patterning compound to the substrate. This may requirecoating of the microscope tip with hydrophobic compounds if thenanolithography is to be performed in air. Solubility characteristics ofthe “ink” molecules in a given solvent can create difficulty inestablishing a desired line width and a suitable loading concentrationof the ink in the solvent. Furthermore, surface tension characteristicsof different solvents can lead to drip or rapid flow from the penleading to problems with precise control of the ink application undersome circumstances. Accordingly, additional and improved lithographytechniques that could overcome these problems and extend the applicationto pattern with whiskers, clusters and nanocrystals as well as increasedrates of deposition would be highly desirable for use in a variety offields.

SUMMARY OF THE INVENTION

One aspect of the invention provides a method of Dip Pen Lithography(DPN) in which the movement of the molecules to be deposited orpatterned on the substrate (the deposition compound or the patterningcompound) from the tip to the substrate is controlled by a drivingforce. The driving force can be magnetic, chemical, electrical oranother analogous driving force capable of exerting control over themovement of the deposition compounds. This control can provide the addedadvantage of greatly increasing the control over the rate of depositionof the deposition compounds from the tip to the substrate.

Another aspect of the present invention provides a method ofnanolithography referred to herein as Aperture Pen Nanolithography(APN). This method comprises providing a substrate and a depositioncompound in a cavity within a scanning probe microscope tip. Thedeposition compound is applied to the substrate using an electrical,magnetic, chemical or analogous driving force. The tip is used to hold areservoir of the deposition compound and to restrict the transfer of thedeposition compound to the substrate as governed by the applicabledriving force. Following transfer from the tip to the substrate, thedeposition compound attaches to the substrate.

Another aspect of the present invention provides a scanning probemicroscope tip with an internal cavity that acts as the reservoir forthe deposition compound and has an external opening through which thedeposition compound can pass to transfer to the substrate. The externalopening contains a size-restricted aperture such that a depositioncompound cannot successfully transfer from within the tip to thesubstrate in the absence of the appropriate driving force. The drivingforce is supplied in the form of an electrical, magnetic, chemical oranalogous force sufficient to move the molecules of the depositioncompound to the substrate through the size-restricted aperture wherethey may interact, such as by chemically interacting, to become bound tothe substrate.

In another aspect, the invention provides a nanolithography devicehaving a scanning probe microscope tip with an internal cavity having anexternal opening containing a size- or shape-selective aperture. Theaperture may be formed in a variety of materials such as a polymer gel,an ultra thin membrane or an ultra thin crystal. The aperture controlsthe movement of molecules from within the cavity under an applicabledriving force to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic representation of Dip Pen Nanolithography(DPN). The present invention uses a driving force to control themovement of the deposition compound from the AFM tip to the substrate.

FIG. 2A shows the top view enlargement of a fabricated microcontainer ofthe present invention.

FIG. 2B shows a side view enlargement of the microcontainer of FIG. 1A.

FIG. 2C shows a side view enlargement of the microcontainer of thepresent invention suspended in liquid containing a deposition compound.

FIG. 3 is a schematic of a microcontainer of the present inventionloaded with deposition compound for delivery through the aperture at thetip of the microcontainer to the substrate under an electrical drivingforce.

DETAILED DESCRIPTION OF THE INVENTION A. Dip Pen Nanolithography

The invention provides a method of nanolithography for preciselypatterning or depositing molecules on a substrate to form thin filmnanostructures. The invention further provides an improved method of DPNin which the rate and extent of the movement of the deposition compoundfrom the tip to the substrate is controlled by a driving force.

To practice DPN, a scanning probe microscope (SPM) tip is coated with apatterning compound. This can be accomplished in a number of ways. Forinstance, the tip can be coated by vapor deposition, by direct contactscanning, or by bringing the tip into contact with a solution of thepatterning compound.

The simplest method of coating the tips is by direct contact scanning.Coating by direct contact scanning is accomplished by depositing a dropof a saturated solution of the patterning compound on a solid substrate(e.g., glass or silicon nitride; available from Fisher Scientific orMEMS Technology Application Center). Upon drying, the patterningcompound forms a microcrystalline phase on the substrate. To coat thepatterning compound on the SPM tip, the tip is scanned repeatedly acrossthis microcrystalline phase. While this method is simple, it does notlead to the best loading of the tip, since it is difficult to controlthe amount of patterning compound transferred from the substrate to thetip.

The tips can also be coated by vapor deposition. See Sherman, ChemicalVapor Deposition For Microelectronics: Principles, Technology AndApplications (Noyes, Park Ridges, N.J., 1987. Briefly, a patterningcompound (in pure form, solid or liquid, no solvent) is placed on asolid substrate (e.g., glass or silicon nitride; obtained from FisherScientific or MEMS Technology Application Center), and the tip ispositioned near (within about 1-20 cm, depending on chamber design) thepatterning compound. The compound is then heated to a temperature atwhich it vaporizes, thereby coating the tip with the compound. Forinstance, 1-octadecanethiol can be vapor deposited at 60° C. Coating byvapor deposition should be performed in a closed chamber to preventcontamination of other areas. If the patterning compound is one which isoxidized by air, the chamber should be a vacuum chamber or anitrogen-filled chamber. Coating the tips by vapor deposition producesthin, uniform layers of patterning compounds on the tips and gives veryreliable results in DPN.

Preferably, however, the SPM tip is coated by dipping the tip into asolution of the patterning compound. The solvent is not critical; allthat is required is that the compound be in solution. However, thesolvent is preferably the one in which the patterning compound is mostsoluble. Also, the solution is preferably a saturated solution. Inaddition, the solvent is preferably one that adheres to (wets) the tip(uncoated or coated with an adhesion layer) very well. The tip ismaintained in contact with the solution of the patterning compound for atime sufficient for the compound to coat the tip. Such times can bedetermined empirically. Generally, from about 30 seconds to about 3minutes is sufficient. Preferably, the tip is dipped in the solutionmultiple times, with the tip being dried between each dipping. Thenumber of times a tip needs to be dipped in a chosen solution can bedetermined empirically. Preferably, the tip is dried by blowing an inertgas (such as carbon tetrafluoride,1,2-dichloro-1,1,2,2,-tetrafluoroethane, dichlorodifluoromethane,octafluorocyclobutane, trichlorofluoromethane, difluoroethane, nitrogen,nitrogen, argon or dehumidified air) not containing any particles (i.e.,purified) over the tip. Generally, about 10 seconds of blowing with thegas at room temperature is sufficient to dry the tip. After dipping (thesingle dipping or the last of multiple dippings), the tip may be usedwet to pattern the substrate, or it may be dried (preferably asdescribed above) before use. A dry tip gives a low, but stable, rate oftransport of the patterning compound for a long time (on the order ofweeks), whereas a wet tip gives a high rate of transport of thepatterning compound for a short time (about 2-3 hours). A dry tip ispreferred for compounds having a good rate of transport under dryconditions, whereas a wet tip is preferred for compounds having a lowrate of transport under dry conditions.

To perform this embodiment of DPN under the control of a driving force,the coated tip is brought into close contact or into actual contact witha substrate. Thus, the tip is “in contact” with the substrate when it isclose enough so that a meniscus forms. Alternatively, the tip may beheld in close contact with the substrate but kept a suitable distancefrom the substrate such that the formation of a meniscus is prevented.The applicable driving force is then applied or modified to cause thedeposition compound to move from the tip to the substrate. Suitablesolvents, also referred to as transport media, include water,hydrocarbons (e.g., hexane), and solvents in which the patterningcompounds are soluble. Faster writing with the tip can be accomplishedby using the transport medium in which the patterning compound is mostsoluble. Ultimately, the rate at which the writing can be accomplishedis controlled by the application of the driving force applied to the tipand/or substrate.

B. Aperture Pen Nanolithography

The invention also provides a method of nanolithography using a deliverydevice capable of controlled, site-specific delivery and deposition ofsize-selected molecules, whiskers, clusters and nanocrystals onsubstrate surfaces and methods of using the same. The device is a tipwith an internal cavity having a narrow opening at the end allowing sizeor shape-restricted delivery of a deposition compound in the internalcavity onto the surface of the substrate. A variation of such tips usinga cantilevered micropipette has been previously described by Lewis etal. (Applied Physics Letters, 75, 2689 (1999)s). The opening in the endof the tip is sufficiently small to create a capillary force preventingdelivery of fluid through the narrow opening while the size- orshape-specific aperture limits transport of molecules or other entitiesto only those which can physically pass through the aperture openingunder the driving force. Suitable tips include SPM tips modified tocontain a reservoir with an external opening controlled by an aperture,and tips having similar properties, including tips made especially forAPN using the guidelines provided herein. As used in this application,the phrases “scanning probe microscope tips” and “SPM tips” mean tipsused in atomic scale imaging. Suitable SPM tips include AFM tips, nearfield scanning optical microscope (NSOM) tips, and scanning tunnelingmicroscope (STM) tips. NSOM tips are hollow, and the depositioncompounds are loaded in the hollows of the NSOM tips which serve asreservoirs of the deposition compound to produce a virtual fountain penwhen combined with an appropriate aperture thereby forming an APN tipaccording to the present invention. Many suitable SPM tips are availablecommercially (e.g. from Park Scientific, Digital Instruments, MolecularImaging, Thermomicroscopes, Digital Instruments Nanonics Ltd. andTopometrix). Alternatively, SPM tips can be made by methods well knownin the art. For instance, SPM tips can be made by e-beam lithography.The APN tips may be made to include a nanotube. This embodiment mayresemble a nanotube mounted tip. Preferably, the nanotube is a carbonnanotube. Most preferably, the tip is an AFM tip. Any AFM tip can beused, and suitable AFM tips include those that are availablecommercially from, e.g., Park Scientific, Digital Instruments andMolecular Imaging.

The aperture on the tip can be useful at any size sufficiently narrow tocreate a capillary force such that the deposition compound cannot run,drip or otherwise move from the tip to the substrate surface through theaperture without the application of a driving force sufficient toovercome the capillary force. Typically, an aperture with an internaldiameter of less than 200 nm is sufficiently narrow. Preferably, theaperture has an internal diameter of between about 0.2 nm and about 200nm, more preferably, the aperture has an internal diameter of betweenabout 0.5 nm and about 50 nm, more preferably the aperture has aninternal diameter of between about 1 nm and about 20 nm, even morepreferably, aperture has an internal diameter of between about 2 nm andabout 10 nm. The narrow aperture on the SPM tip of the present inventioncan be made by several means, for example focused ion beam,mechanical/ion polishing of narrow tip-cones or by high-energy electronbeam induced “drilling” of ultra-thin membranes (e.g. 2-10 nm thickSiO₂, Si₃N₄ or amorphous carbon). Several materials undergo atomicsputtering under high-energy, high-intensity electron beam exposures. Ifsuch exposures are limited to small dimensions, as is the case with afocused electron probe on the specimen surface, the material under theelectron beam can knock-off atoms, eventually creating holes of a sizeon the order of the electron beam diameter. Through MEMS technology, amicrocontainer (e.g. AFM cantilever prism) can be created withultra-thin membrane(s) at the bottom. This MEMS microcontainer can beloaded onto a TEM/STEM specimen holder for electron beam drillingexperiments. A high energy (100-1000 keV) electron beam is then focusedonto a small spot limited only by the narrowest electron beam size,which in modern TEMs/STEMs can be as small as 0.2-0.5 nm. Subsequentinelastic scattering and direct atomic sputtering by prolongedhigh-energy electron beam exposure results in local mass loss within theirradiated region. This eventually results in formation of nano-holes ofa size on the order of the beam diameter. By selecting different shapesof the electron beam (e.g. circular, square etc.), differently shapedholes can be drilled. Alternatively, using appropriate crystallographicorientation of ultra-thin crystalline membranes, holes which conform tocrystallography of the ultra-thin film may be formed. For example,oriented ultra-thin MgO may produce a square-shaped nanohole, while anoriented sapphire (single crystals of Al₂O₃) ultra-thin film willproduce a hexagonal-shaped nanohole. Other crystalline membranes thatare useful include, but are not limited to, diamond, and intermetallicor compound semiconductors, preferably type III-V semiconductors andtype II-VI semiconductors. The deposition compound delivered throughthis external opening or aperture is then deposited on the substrate ata spatial resolution consistent with the aperture opening in the rangeof about 0.2 nm to about 100 nm.

APN tips can be loaded with the deposition compound in a variety ofways. When the internal cavity is to be loaded with a solution of thedeposition compound the solution, preferably a saturated solution, isinjected or otherwise transported into the cavity. This loading can alsobe done by soaking the tip in the appropriate deposition compoundsolution. Similar to DPN tips, the APN tips can also be loaded by vapordeposition, by direct contact scanning, or by bringing the tip intocontact with a solution of the patterning compound.

C. Driving Forces

The present invention involves the use of electrical, magnetic, chemicalor analogous driving forces to transfer molecules, whiskers, clusters ornanocrystals from the tip to the substrate. The driving force causes thephysical movement of the deposition compound from the tip to thesubstrate. This greatly increases the control over the movement of thedeposition compound making it possible to create size-selective andsite-specific coverage of individual molecules and precisely formed thinfilm nanostructures. Additionally, the driving force can be used tocontrol the rate of deposition making it possible to decrease orincrease the speed with which the deposition compound moves from the DPNor APN tips to the substrate. In one embodiment of the present inventionthe driving force is used to control movement of the deposition compoundfrom a DPN tip to the substrate. In this embodiment, the DPN tip has thedeposition compound loaded on the surface of the tip and may include anappropriate solvent. The DPN tip is then moved into close proximity ofthe substrate or moved to make contact with the substrate. Thedeposition compound is then moved from the tip to the substrate byeither applying or changing the appropriate driving force. For example,if the deposition compound is a magnetic compound such as nickel or ironor a magnetically tagged compound, the appropriate driving force may bea magnetic field of a larger magnitude applied to the substrate.Alternatively, the magnetic filed may be reversed between the tip andthe substrate causing a magnetic deposition compound to move away fromthe tip to the substrate. As another example, the deposition compoundmay be a negatively or positively charged compound and the appropriatedriving force may be an electrical driving force. The electricity maythen be precisely controlled and applied to the substrate, to the tip orto both the substrate and the tip to control the movement of depositioncompounds from the tip to the substrate. Alternatively, the electricitymay be continuously present in either the tip or the substrate or bothand the movement of the deposition compound to the substrate may beprecisely controlled by modulation of the electrical current alreadypresent. This embodiment makes it possible to modulate the rate ofdeposition or patterning by control over the applicable driving force.

In another embodiment of the present invention the driving force is usedto control movement of the deposition compound from the APN tip to thesubstrate through well-defined and size-selective apertures fabricatedby a variety of mechanisms for nanoscale to sub-nanometer (nm) scalefeatures. In this way, the cross-section of the aperture can be formedto be consistent with the cross-section geometry of the molecule ormaterials that are to be transported through the aperture, similar tosieving coins or shape-specific objects. In this embodiment, the drivingforce is applied to overcome the limitation of capillary action whichprecludes delivery of the deposition compound through the narrow openingdefined by the capillary forces, while the size-specific aperture limitstransport of molecules or other entities to only those which canphysically pass through the aperture opening. For example, gelelectrophoresis is a well-know and widely-used technique to separate DNAmolecules based on size/mass. This technique relies on the transport ofnegatively-charged DNA molecules through the nanoscale pores ofpolymeric gels under the influence of an electrical field across thegel. A novel approach to deposit/pattern single or multiple DNAmolecules on a substrate involves a reservoir containing DNA molecules,for instance in an AFM cantilever prism (see FIG. 2), having a narrowopening with a diameter of between about 2 nm and about 15 nm at theend. At this diameter, the viscosity and capillary effects dominate anddo not permit “dripping” of the liquid through such narrow opening.However, when the tip is closely approached by a positively-biasedsubstrate (e.g. gold), the negatively-charged DNA is attracted to thepositively-charged substrate, analogous to gel electrophoresis. Thisallows the transfer of DNA molecules directly onto the substrate. If theDNAs are “thiolated,” the thiol groups bond to the gold surface creatinga monolayer coverage of single DNA molecules wherever the AFM tip isbrought close enough to the positively-biased substrate surface. If theaperture of the AFM opening is made small enough, as for example, thediameter of single DNA strand, only one DNA strand is transferredthrough the aperture onto the substrate, allowing, for the first time,size-selective and site-specific coverage and patterning with singlemolecules.

Thus, by creating a stimulus for transport of charged molecules viasubstrate bias and by controlling the aperture opening by size- andshape-specific method, a variety of molecules are transferred onto anactive substrate. The stimulus may be electrical bias of the substrate(for example to transport charged molecules such as DNA) or magnetic (totransport magnetically active molecules) or chemical (to exploitchemical interactions to control movement of deposition compounds). Thechemical interaction may be a natural chemical interaction that takesplace between the deposition compound and the substrate or moleculesaffixed to the surface of the substrate. The chemical interaction mayalso arise between a deposition compound or a chemical on the surface ofthe substrate modified or tagged with a chemical such that a chemicalinteraction can take place between the substrate and the depositioncompound. The chemical interaction will typically be a chemicalattraction between the deposition compound and the substrate and themodification of this chemical attraction can be used to control theextent and the rate of the movement of the deposition compound from thetip to the substrate. For example, the driving force may be a chemicaldriving force created by a substrate having a chemical attraction to thedeposition compound. Further, by fabricating the aperture opening of theAPN tip to size and shape specificity, the transfer can be extended toinclude other structures such as whiskers (nanowires), clusters (e.g.proteins) and nanoparticles (e.g. magnetic or electrostaticallycharged). The aperture may be fabricated to include specific shapes suchas circles, squares, triangles, ellipses, or other polygons.

D. Coated Tips

When an atomic force microscope is operated in air, water condensesbetween the tip and surface to form a meniscus and then is transportedby means of the meniscus as the tip is scanned across the surface. Thisfilled meniscus, and the capillary force associated with it,significantly impede the operation of the APN and substantially affectthe imaging process.

Quite surprisingly, it has been found that AFM tips coated with certainhydrophobic compounds exhibit an improved ability to image substrates inair by AFM as compared to uncoated tips. The reason for this is that thehydrophobic molecules reduce the size of the water meniscus formed andeffectively reduce friction. As a consequence, the resolution of AFM inair is increased using a coated tip, as compared to using an uncoatedtip. Accordingly, coating tips with the hydrophobic molecules can beutilized as a general pretreatment for both DPN and APN tips forperforming DPN and/or APN in air or in circumstances when it isimportant to prevent formation of a meniscus between the tip and thesubstrate.

Hydrophobic compounds useful for coating AFM tips must form a uniformthin coating on the tip surface, must not bind covalently to thesubstrate being imaged or to the tip, must bind to the tip more stronglythan to the substrate, and must stay solid at the temperature of AFMoperation. Suitable hydrophobic compounds include those hydrophobiccompounds described above for use as deposition compounds, provided thatsuch hydrophobic deposition compounds are not used to coat AFM tipswhich are used to image a corresponding substrate for the depositioncompound or to coat AFM tips which are made of, or coated with,materials useful as the corresponding substrate for the depositioncompound. Preferred hydrophobic compounds for most substrates are thosehaving the formula RNH₂, wherein R is an alkyl of the formulaCH₃(CH₂)_(n) or an aryl, and n is 0-30, preferably 10-20 (see discussionof deposition compounds above). Particularly preferred is 1-dodecylaminefor AFM temperatures of operation below 74° F. (about 23.3° C.).

The tips may also be coated with a hydrophilic compound for use incertain applications. For example the tip may be coated with compoundsthat interact chemically with the deposition compound or the substrate.This may require the use of chemical coatings on the tips that arehydrophilic in nature.

AFM tips can be coated with the hydrophobic or hydrophilic compounds ina variety of ways. Suitable methods include those described above forcoating AFM tips with patterning compounds for use in DPN. Preferably,the AFM tip is coated with a hydrophobic compound by simply dipping thetip into a solution of the compound for a sufficient time to coat thetip and then drying the coated tip with an inert gas, either afterformation of the aperture if the aperture materials and the treatment iscompatible or before aperture formation if the aperture is deleteriouslyaffected by the treatments. After the tip is coated, APN is performed inthe same manner as it would be if the tip were not coated. No changes inAPN procedures have been found necessary.

The tip in APN is used to form a desired pattern or to providesize-selective, site-specific coverage with single molecules of thedeposition compound on the substrate. The pattern may be any pattern andmay be simple or complex. For instance, the pattern may be a dot, aline, a cross, a geometric shape (e.g., a triangle, square or circle),combinations of two or more of the foregoing, arrays (e.g., a squarearray of rows and columns of dots), electronic circuits, or part of, ora step in, the formation of three-dimensional structures, whiskers,clusters, nanocrystals and even single molecules.

E. The Substrate

The substrate may be of any shape and size. In particular, the substratemay be flat or curved. Substrates may be made of any material which canbe modified by a deposition compound to form stable surface structuresand can be subjected to electrical, magnetic, chemical or analogousforces to create the driving force for movement of the depositioncompound from the tip to the substrate. Substrates useful in thepractice of the invention include metals (e.g., gold, silver, aluminum,copper, platinum, and paladium), metal oxides (e.g., oxides of Al, Ti,Fe, Ag, Zn, Zr, In, Sn and Cu), semiconductor materials (e.g., Si, CdSe,CdS and CdS coated with ZnS), magnetic materials (e.g., ferromagnetite),polymers or polymer-coated substrates, superconductor materials(YBa₂Cu₃O_(7-δ)), Si, SiO₂, glass, AgI, AgBr, HgI₂, PbS, PbSe, ZnSe,ZnS, ZnTe, CdTe, InP, In₂O₃/SnO₂, In₂S₃, In₂Se₃, In₂Te₃, Cd₃P₂, Cd₃As₂,InAs, ALAs, GaP, GaAs, and indium tin oxide. Methods of making suchsubstrates are well-known in the art and include evaporation andsputtering (metal films), crystal semiconductor growth (e.g., Si, Ge,GaAs), chemical vapor deposition (semiconductor thin films), epitaxialgrowth (crystalline semiconductor thin films), and thermal shrinkage(oriented polymers). See, e.g., Alcock et al., Canadian MetallurgicalQuarterly, 23, 309 (1984); Holland, Vacuum Deposition of Thin Films(Wiley, New York 1956); Grove, Philos. Trans. Faraday Soc., 87 (1852);Teal, IEEE Trans. Electron Dev. ED-23, 621 (1976); Sell, Key Eng.Materials, 58, 169 (1991); Keller et al., Float-Zone Silicon (MarcelDekker, New York, 1981); Sherman, Chemical Vapor Deposition ForMicroelectronics: Principles, Technology And Applications (Noyes, ParkRidges, N.J., 1987); Epitaxial Silicon Technology (Baliga, ed., AcademicPress, Orlando, Fla., 1986); U.S. Pat. No. 5,138,174; Hidber et al.,Langmuir, 12, 5209-5215 (1996). Suitable substrates can also be obtainedcommercially from, e.g., Digital Instruments (gold), Molecular Imaging(gold), Park Scientific (gold), Electronic Materials, Inc.(semiconductor wafers), Silicon Quest, Inc. (semiconductor wafers), MEMSTechnology Applications Center, Inc. (semiconductor wafers), CrystalSpecialties, Inc. (semiconductor wafers), Siltronix, Switzerland(silicon wafers), Aleene's, Buellton, Calif. (biaxially-orientedpolystyrene sheets), and Kama Corp., Hazelton, Pa. (oriented thin filmsof polystyrene). Gold substrates are preferred.

F. Deposition Compounds

Any deposition compound can be used, provided it is capable oftransferring to the substrate, under the influence of a driving force,to modify the substrate to form stable surface structures. Stablesurface structures are formed by chemisorption or physisorption of themolecules of the deposition compound onto the substrate or by covalentlinkage of the molecules of the deposition compound to the substrate.Useful compounds include magnetic particles or biomolecules such asproteins, peptides, polypeptides, nucleotides, polynucleotides, nucleicacids and synthetic organic compounds. Additionally, biomolecules bound,adsorbed or absorbed to magnetic particles are particularly useful.

Many suitable compounds which can be used as the deposition compound,and the corresponding substrate(s) for the compounds, are known in theart. For example:

-   -   a. Compounds of the formula R₁SH, R₁SSR₂, R₁SR₂, R₁SO₂H, (R₁)₃P,        R₁NC, R₁CN, (R₁)₃N, R₁OOH, or ArSH can be used to pattern gold        substrates;    -   b. Compounds of formula R₁SH, (R₁)₃N, or ArSH can be used to        pattern silver, copper, palladium and semiconductor substrates;    -   c. Compounds of the formula R₁NC, R₁SH, R₁SSR₂, or R₁SR₂ can be        used to pattern platinum substrates;    -   d. Compounds of the formula R₁SH can be used to pattern        aluminum, TiO₂, SiO₂, GaAs and InP substrates;    -   e. Organosilanes, including compounds of the formula R₁SiCl₃,        R₁Si(OR₂)₃, (R₁COO)₂, R₁CH═CH₂, R₁Li or R₁MgX, can be used to        pattern Si, SiO₂ and glass substrates;    -   f. Compounds of the formula R₁COOH or R₁CONHR₂ can be used to        pattern metal oxide substrates;    -   g. Compounds of the formula R₁SH, R₁NH₂, ArNH₂, pyrrole, or        pyrrole derivatives wherein R₁ is attached to one of the carbons        of the pyrrole ring, can be used to pattern cuprate high        temperature superconductors;    -   h. Compounds of the formula R₁PO₃H₂ can be used to pattern ZrO₂        and In₂O₃/SnO₂ substrates;    -   i. Compounds of the formula R₁COOH can be used to pattern        aluminum, copper, silicon and platinum substrates;    -   j. Compounds that are unsaturated, such as azoalkanes (R₃NNR₃)        and isothiocyanates (R₃NCS), can be used to pattern silicon        substrates;    -   k. Proteins and peptides can be used to pattern, gold, silver,        glass, silicon, and polystyrene; and    -   l. Silazanes can be used to pattern SiO₂ and oxidized GaAs.        In the above formulas:

R₁ and R₂ each has the formula X(CH₂)n and, if a compound is substitutedwith both R₁ and R₂, then R₁ and R₂ can be the same or different;

R₃ has the formula CH₃(CH₂)_(n);

n is 0-30;

Ar is an aryl;

X is —CH₃, —CHCH₃, —COOH, —CO₂(CH₂)_(m)CH₃, —OH, —CH₂OH, ethyleneglycol, hexa(ethylene glycol), —O(CH₂)_(m)CH₃, —NH₂, —NH(CH₂)_(m)NH₂,halogen, glucose, maltose, fullerene C60, a nucleotide, anoligonucleotide, a nucleic acid (DNA, RNA, etc.), a protein (e.g., anantibody or enzyme) or a ligand (e.g., an antigen, enzyme substrate orreceptor); and

m is 0-30.

For a description of deposition compounds and their preparation and use,see Xia and Whitesides, Angew. Chem. Int. Ed., 37, 550-575 (1998) andreferences cited therein; Bishop et al., Curr. Opinion Colloid &Interface Sci., 1, 127-136 (1996); Calvert, J. Vac. Sci. Technol. B, 11,2155-2163 (1993); Ulman, Chem. Rev., 96:1533 (1996) (alkanethiols ongold); Dubois et al., Annu. Rev. Phys. Chem., 43:437 (1992)(alkanethiols on gold); Ulman, An Introduction to Ultrathin OrganicFilms: From Langmuir-Blodgett to Self-Assembly (Academic, Boston, 1991)(alkanethiols on gold); Whitesides, Proceedings of the Robert A. WelchFoundation 39th Conference On Chemical Research Nanophase Chemistry,Houston, Tex., pages 109-121 (1995) (alkanethiols attached to gold);Mucic et al. Chem. Commun. 555-557 (1996) (describes a method ofattaching 3′ thiol DNA to gold surfaces); U.S. Pat. No. 5,472,881(binding of oligonucleotide-phosphorothiolates to gold surfaces);Burwell, Chemical Technology, 4, 370-377 (1974) and Matteucci andCaruthers, J. Am. Chem. Soc., 103, 3185-3191 (1981) (binding ofoligonucleotides-alkylsiloxanes to silica and glass surfaces); Grabar etal., Anal. Chem., 67, 735-743 (binding of aminoalkylsiloxanes and forsimilar binding of mercaptoalkylsiloxanes); Nuzzo et al., J. Am. Chem.Soc., 109, 2358 (1987) (disulfides on gold); Allara and Nuzzo, Langmuir,1, 45 (1985) (carboxylic acids on aluminum); Allara and Tompkins, J.Colloid Interface Sci., 49, 410-421 (1974) (carboxylic acids on copper);Iler, The Chemistry Of Silica, Chapter 6, (Wiley 1979) (carboxylic acidson silica); Timmons and Zisman, J. Phys. Chem., 69, 984-990 (1965)(carboxylic acids on platinum); Soriaga and Hubbard, J. Am. Chem. Soc.,104, 3937 (1982) (aromatic ring compounds on platinum); Hubbard, Acc.Chem. Res., 13, 177 (1980) (sulfolanes, sulfoxides and otherfunctionalized solvents on platinum); Hickman et al., J. Am. Chem. Soc.,111, 7271 (1989) (isonitriles on platinum); Maoz and Sagiv, Langmuir, 3,1045 (1987) (silanes on silica); Maoz and Sagiv, Langmuir, 3, 1034(1987) (silanes on silica); Wasserman et al., Langmuir, 5, 1074 (1989)(silanes on silica); Eltekova and Eltekov, Langmuir, 3, 951 (1987)(aromatic carboxylic acids, aldehydes, alcohols and methoxy groups ontitanium dioxide and silica); and Lec et al., J. Phys. Chem., 92, 2597(1988) (rigid phosphates on metals); Lo et al., J. Am. Chem. Soc., 118,11295-11296 (1996) (attachment of pyrroles to superconductors); Chen etal., J. Am. Chem. Soc., 117, 6374-5 (1995) (attachment of amines andthiols to superconductors); Chen et al., Langmuir, 12, 2622-2624 (1996)(attachment of thiols to superconductors); McDevitt et al., U.S. Pat.No. 5,846,909 (attachment of amines and thiols to superconductors); Xuet al., Langmuir, 14, 6505-6511 (1998) (attachment of amines tosuperconductors); Mirkin et al., Adv. Mater. (Weinheim, Ger.), 9,167-173 (1997) (attachment of amines to superconductors); Hovis et al.,J. Phys. Chem. B, 102, 6873-6879 (1998) (attachment of olefins anddienes to silicon); Hovis et al., Surf. Sci., 402-404, 1-7 (1998)(attachment of olefins and dienes to silicon); Hovis et al., J. Phys.Chem. B, 101, 9581-9585 (1997) (attachment of olefins and dienes tosilicon); Hamers et al., J. Phys. Chem. B, 101, 1489-1492 (1997)(attachment of olefins and dienes to silicon); Hamers et al., U.S. Pat.No. 5,908,692 (attachment of olefins and dienes to silicon); Ellison etal., J. Phys. Chem. B, 103, 6243-6251 (1999) (attachment ofisothiocyanates to silicon); Ellison et al., J. Phys. Chem. B, 102,8510-8518 (1998) (attachment of azoalkanes to silicon); Ohno et al.,Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A, 295, 487-490 (1997)(attachment of thiols to GaAs); Reuter et al., Mater. Res. Soc. Symp.Proc., 380, 119-24 (1995) (attachment of thiols to GaAs); Bain, Adv.Mater. (Weinheim, Fed. Repub. Ger.), 4, 591-4 (1992) (attachment ofthiols to GaAs); Sheen et al., J. Am. Chem. Soc., 114, 1514-15 (1992)(attachment of thiols to GaAs); Nakagawa et al., Jpn. J. Appl. Phys.,Part 1, 30, 3759-62 (1991) (attachment of thiols to GaAs); Lunt et al.,J. Appl. Phys., 70, 7449-67 (1991) (attachment of thiols to GaAs); Luntet al., J. Vac. Sci. Technol., B, 9, 2333-6 (1991) (attachment of thiolsto GaAs); Yamamoto et al., Langmuir ACS ASAP, web release numberIa990467r (attachment of thiols to InP); Gu et al., J. Phys. Chem. B,102, 9015-9028 (1998) (attachment of thiols to InP); Menzel et al., Adv.Mater. (Weinheim, Ger.), 11, 131-134 (1999) (attachment of disulfides togold); Yonezawa et al., Chem. Mater., 11, 33-35 (1999) (attachment ofdisulfides to gold); Porter et al., Langmuir, 14, 7378-7386 (1998)(attachment of disulfides to gold); Son et al., J. Phys. Chem., 98,8488-93 (1994) (attachment of nitrites to gold and silver); Steiner etal., Langmuir, 8, 2771-7 (1992) (attachment of nitrites to gold andcopper); Solomun et al., J. Phys. Chem., 95, 10041-9 (1991) (attachmentof nitrites to gold); Solomun et al., Ber. Bunsen-Ges. Phys. Chem., 95,95-8 (1991) (attachment of nitrites to gold); Henderson et al., Inorg.Chim. Acta, 242, 115-24 (1996) (attachment of isonitriles to gold); Hucet al., J. Phys. Chem. B, 103, 10489-10495 (1999) (attachment ofisonitriles to gold); Hickman et al., Langmuir, 8, 357-9 (1992)(attachment of isonitriles to platinum); Steiner et al., Langmuir, 8,90-4 (1992) (attachment of amines and phosphines to gold and attachmentof amines to copper); Mayya et al., J. Phys. Chem. B, 101, 9790-9793(1997) (attachment of amines to gold and silver); Chen et al., Langmuir,15, 1075-1082 (1999) (attachment of carboxylates to gold); Tao, J. Am.Chem. Soc., 115, 4350-4358 (1993) (attachment of carboxylates to copperand silver); Laibinis et al., J. Am. Chem. Soc., 114, 1990-5 (1992)(attachment of thiols to silver and copper); Laibinis et al., Langmuir,7, 3167-73 (1991) (attachment of thiols to silver); Fenter et al.,Langmuir, 7, 2013-16 (1991) (attachment of thiols to silver); Chang etal., Am. Chem. Soc., 116, 6792-805 (1994) (attachment of thiols tosilver); Li et al., J. Phys. Chem., 98, 11751-5 (1994) (attachment ofthiols to silver); Li et al., Report, 24 pp (1994) (attachment of thiolsto silver); Tarlov et al., U.S. Pat. No. 5,942,397 (attachment of thiolsto silver and copper); Waldeck, et al., PCT application WO/99/48682(attachment of thiols to silver and copper); Gui et al., Langmuir, 7,955-63 (1991) (attachment of thiols to silver); Walczak et al., J. Am.Chem. Soc., 113, 2370-8 (1991) (attachment of thiols to silver);Sangiorgi et al., Gazz. Chim. Ital., 111, 99-102 (1981) (attachment ofamines to copper); Magallon et al., Book of Abstracts, 215th ACSNational Meeting, Dallas, Mar. 29-Apr. 2, 1998, COLL-048 (attachment ofamines to copper); Patil et al., Langmuir, 14, 2707-2711 (1998)(attachment of amines to silver); Sastry et al., J. Phys. Chem. B, 101,4954-4958 (1997) (attachment of amines to silver); Bansal et al., J.Phys. Chem. B, 102, 4058-4060 (1998) (attachment of alkyl lithium tosilicon); Bansal et al., J. Phys. Chem. B, 102, 1067-1070 (1998)(attachment of alkyl lithium to silicon); Chidsey, Book of Abstracts,214th ACS National Meeting, Las Vegas, Nev., Sep. 7-11, 1997, I&EC-027(attachment of alkyl lithium to silicon); Song, J. H., Thesis,University of California at San Diego (1998) (attachment of alkyllithium to silicon dioxide); Meyer et al., J. Am. Chem. Soc., 110,4914-18 (1988) (attachment of amines to semiconductors); Brazdil et al.J. Phys. Chem., 85, 1005-14 (1981) (attachment of amines tosemiconductors); James et al., Langmuir, 14, 741-744 (1998) (attachmentof proteins and peptides to glass); Bernard et al., Langmuir, 14,2225-2229 (1998) (attachment of proteins to glass, polystyrene, gold,silver and silicon wafers).

G. Multiple Tip Nanolithography

Single tips can be used to produce one or more patterns of a depositioncompound on a substrate. Alternatively, a plurality of tips can be usedin a single or similar device to produce a plurality of patterns (thesame pattern or different patterns) on the substrate (see, e.g., U.S.Pat. Nos. 5,630,923, and 5,666,190, Lutwyche et al., Sens. Actuators A,73:89 (1999), Vettiger et al., Microelectron Eng., 46:11 (1999), Minneet al., Appl. Phys. Lett., 73:1742 (1998), and Tsukamoto et al., Rev.Sci. Instrum., 62:1767 (1991) which describe devices comprising multiplecantilevers and tips for patterning a substrate). When a plurality oftips is used, the tips can be used serially or in parallel to producepatterns on the substrate.

If patterns of more than one deposition compound overlapping on thesubstrate are desired, any unbound first deposition compound must beremoved from the substrate before applying a second deposition compound.The unbound first deposition compound can be removed by rinsing thesubstrate. Any solvent or solution and conditions may be used that arenot harmful to the deposition compound attached to the substrate. Afterremoval of the unbound first deposition compound, a second depositioncompound is applied to at least a portion of the substrate. The seconddeposition compound is applied in the same manner as described above. Adesired pattern of the second deposition compound on the substrate isproduced in the same manner as described above using one or a pluralityof tips substantially free of the first deposition compound. A tipsubstantially free of the first deposition compound can be a new tip orit can be the tip used to apply the first deposition compound which hasbeen cleaned to remove the first deposition compound. The cleaning oftips can be accomplished by rinsing them in a solvent in which thedeposition compound is soluble (e.g., by simply dipping the tips in thesolvent). The solvent is preferably the solvent in which the depositioncompound is most soluble. These steps can be repeated as many times asnecessary to pattern the substrate with as many different depositioncompounds as desired.

H. Multiple Deposition Compounds

More than one deposition compound can be used to pattern a substratesimultaneously by applying each of the deposition compounds to thesubstrate from a plurality of tips. Each of the deposition compoundsapplied to the substrate by the tips covers only a specific controlledarea dictated by the tip used to apply it. Thus, the plurality of tipsare spaced sufficiently apart and the size of the deposition compoundstructures must be tailored so that there is no overlap of the differentdeposition compounds after they are applied. Of course, the plurality oftips could also be used to produce a plurality of patterns (the samepattern or different patterns) of that deposition compound.

I. Patterns

DPN and APN can be used to prepare arrays, including combinatorialarrays. An “array” is an arrangement of a plurality of discrete sampleareas in a pattern on a substrate. The sample areas may be any shape(e.g., dots, circles, squares or triangles) and may be arranged in anypattern (e.g., rows and columns of discrete sample areas). Each samplearea may contain the same or a different sample as contained in theother sample areas of the array. A “combinatorial array” is an arraywherein each sample area or a small group of replicate sample areas(usually 2-4) contain(s) a sample which is different than that found inother sample areas of the array. A “sample” is a material or combinationof materials to be studied, identified, reacted, etc.

This technique will be particularly useful for the preparation of arrayson the submicrometer scale. An “array on the submicrometer scale” meansthat at least one of the dimensions (e.g., length, width or diameter) ofthe sample areas, excluding the depth, is less than 1 μm. At present,the technique can be used to prepare lines that are about 2 to about 10nm in width. Arrays on a submicrometer scale allow for faster reactiontimes and the use of less reagents than the currently-used microscale(i.e., having dimensions, other than depth, which are 1-999 μm) andlarger arrays. Also, more information can be gained per unit area (i.e.,the arrays are more dense than the currently-used micrometer scalearrays). Finally, the use of submicrometer arrays provides newopportunities for screening. For instance, such arrays can be screenedwith scanning probe microscopes to look for physical changes in thepatterns (e.g., shape, stickiness, height) and/or to identify chemicalspresent in the sample areas, including sequencing of nucleic acids.

Each sample area of an array contains a single sample. For instance, thesample may be a biological material, such as a nucleic acid (e.g., anoligonucleotide, DNA, or RNA), protein or peptide (e.g., an antibody oran enzyme), ligand (e.g., an antigen, enzyme substrate, receptor or theligand for a receptor), or a combination or mixture of biologicalmaterials (e.g., a mixture of proteins). Such materials may be attacheddirectly on a desired substrate or each sample area may contain acompound attached for capturing the biological material. See, e.g., PCTapplications WO 00/04382, WO 00/04389 and WO 00/04390, the completedisclosures of which are incorporated herein by reference. For instance,deposition compounds terminating in certain functional groups (e.g.,—COOH) can bind proteins through a functional group present on, or addedto, the protein (e.g., —NH₂). Also, it has been reported thatpolylysine, which can be attached to the substrate as described above,promotes the binding of cells to substrates. See James et al., Langmuir,14, 741-744 (1998). It has further been reported that cells bind tooctadecanethiol-coated surfaces. As another example, each sample areamay contain a chemical compound (organic, inorganic and compositematerials) or a mixture of chemical compounds. Chemical compounds may bedeposited directly on the substrate or may be attached through afunctional group present on a deposition compound present in the samplearea. From the foregoing, those skilled in the art will recognize that adeposition compound may comprise a sample or may be used to capture asample.

Arrays and methods of using them are known in the art. For instance,such arrays can be used for biological and chemical screenings toidentify and/or quantify a biological or chemical material (e.g.,immunoassays, enzyme activity assays, genomics, and proteomics).Biological and chemical libraries of naturally-occurring or syntheticcompounds and other materials, including cells, can be used, e.g., toidentify and design or refine drug candidates, enzyme inhibitors,ligands for receptors, and receptors for ligands, and in genomics andproteomics. References describing combinatorial arrays and other arraysand their uses include U.S. Pat. Nos. 5,747,334, 5,962,736, and5,985,356, and PCT applications WO 96/31625, WO 99/31267, WO 00/04382,WO 00/04389, WO 00/04390, WO 00/36136, and WO 00/46406.

DPN and APN can also be used in the preparation of three-dimensionalstructures. For instance, the technique can be used to produce one ormore patterns of one or more deposition compounds on a substrate. Thefirst layer of compounds on the substrate will be referred to as thefoundation layer. It will also be appreciated that the foundation layercould be prepared by conventional nanografting. See Xu and Liu,Langmuir, 13, 127-129 (1997) and U.S. Pat. No. 5,922,214. After thefoundation layer is completed, structure-forming compounds are added tothe foundation layer to form the three-dimensional structure. Thethree-dimensional structure may be simple (e.g., addition of onestructure-forming compound to add a single desired feature or propertyto the foundation layer) or complex (e.g., addition of manystructure-forming compounds to add multiple features and/or propertiesand/or to form multiple layers). Three-dimensional structures may be anymicro- or nano-scale device, system, material, etc., and the term“three-dimensional structure” is used herein to distinguish suchstructures from those micro- or nano-scale devices, systems, materials,etc. produced by applying the deposition compounds to the substrate byhigh force nanolithography or nanografting (i.e., those structurescomprised only of the foundation layer).

A structure-forming compound may be any compound that reacts chemicallyor otherwise stably combines (e.g., by hybridization of twocomplimentary strands of nucleic acid) with the deposition compound(s).The structure-forming compound may be one of the deposition compoundsdescribed above or a functionalized deposition compound. By“functionalized” is meant that the deposition compound has been alteredchemically (e.g., a carboxylate group has been reacted with an alcoholto produce an ester or has been reacted with an amino acid to produce apeptide linkage, etc.) or has a physical material (e.g., a nanoparticle)attached to it. The structure-forming compound may also be a compoundthat functionalizes, e.g., a particular deposition compound (e.g.,converting a carboxylate group on deposition compounds to interchainanhydride groups or converting an azide group on the deposition compoundto an amino group), a compound (e.g., a chemical or biological molecule)that has been functionalized to bind to a capture compound (i e., acompound designed to capture chemical, biological molecules or othermaterials). For examples of structure-forming compounds, see Dubois andNuzzo, Annu. Rev. Phys. Chem., 43, 437-63 (1992); Muller et al.,Science, 268, 272 (1995); Bishop and Nuzzo, Current Opinion in Colloid &Interface Science, 1, 127-136 (1996); Yan et al., J. Am. Chem. Soc.,120, 6179-6180 (1998); Yan et al., Langmuir, 15, 1208-1214 (1999);Lahiri et al., Langmuir, 15, 2055-2060 (1999); and Huck et al.,Langmuir, 15, 6862-6867 (1999); PCT applications WO 00/04389, 00/04382,00/04390; and PCT applications WO 98/04740, 01/00876 and 01/51665(oligonucleotides functionalized with nanoparticles and other particlesand their use for detection of nucleic acids and to prepare variousnanostructures and nanomaterials). In a particularly preferredembodiment, at least one of the deposition compounds and at least one ofthe structure-forming compounds comprise nucleic acids (e.g.,oligonucleotides), and the three-dimensional structure is formed, atleast in part, by the hybridization of nucleic acids comprisingcomplementary sequences.

In summary, DPN and APN conducted with the precise control of a drivingforce are powerful methods for size-selective and site-specific coverageand patterning with a wide variety of deposition compounds and evensingle molecules. These are comparable or even higher resolutions thanthose achieved with much more expensive and sophisticated competitivelithographic methods, such as electron-beam lithography. DPN and APN arealso useful tools for creating microscale and nanoscale structures. Forinstance, these nanolithography techniques can be used in thefabrication of microsensors, microreactors, combinatorial arrays,micromechanical systems, microanalytical systems, biosurfaces,biomaterials, microelectronics, microoptical systems, and nanoelectronicdevices. See, e.g., Xia and Whitesides, Angew. Chem. Int. Ed., 37,550-575 (1998).

It is to be noted that the term “a” or “an” entity refers to one or moreof that entity, including mixtures of the entities of two or more of theentities. As such, the terms “a” (or “an”), “one or more” and “at leastone” are used interchangeably herein. It is also to be noted that theterms “comprising,” “including,” and “having” have been usedinterchangeably.

While various embodiments of the present invention have been describedin detail, it is apparent that modifications and adaptations of thoseembodiments will occur to those skilled in the art. However, it is to beexpressly understood that such modifications and adaptations are withinthe spirit and scope of the present invention, as set forth in thefollowing claims.

1. A method of nanolithography, comprising: providing a substrate;providing a tip comprising an internal cavity having an external openingto the surface of said tip, wherein said opening comprises an internaldiameter of less than about 200 nanometers; loading said cavity with adeposition compound, wherein said deposition compound does not passthrough said external opening in the absence of a driving force; andsubjecting said tip to a driving force to deliver said depositioncompound through said external opening to be deposited on saidsubstrate; wherein the driving force is selected from the groupconsisting of an electrical and a magnetic driving force, wherein, forthe electrical driving force, the deposition compound is a chargedcompound subjected to an applied electric field, and wherein, for themagnetic driving force, the deposition compound is a magnetic compoundor a magnetically tagged compound subjected to a magnetic field.
 2. Themethod of claim 1, wherein the substrate is gold and the depositioncompound is a protein or peptide or haste formula R₁SH, R₁SSR₂, R₁SR₂,R₁SO₂H, (R₁)₃P, R₁NC, R₁CN, (R₁)₃N, R₁COOH, or ArSH, wherein: R₁ and R₂each has the formula X(CH₂)_(n) and, if a compound is substituted withboth R₁ and R₂, then R₁ and R₂ can be the same or different; n is 0-30;Ar is an aryl; X is —CH₃, —CHCH₃, —COOH, —CO₂(CH₂)_(m)CH₃, —OH, —CH₂OH,ethylene glycol, hexa(ethylene glycol), —O(CH₂)_(m)CH₃, —NH₂,—NH(CH₂)_(m)NH₂, halogen, glucose, maltose, fullerene C60, a nucleicacid, a protein, or a ligand; and m is 0-30.
 3. The method of claim 2,wherein the deposition compound has the formula R₁SH or ArSH.
 4. Themethod of claim 1, wherein the substrate is aluminum, gallium arsenideor titanium dioxide and the deposition compound has the formula R₁SH,wherein: R₁ has the formula X(CH₂)_(n); n is 0-30; X is —CH₃, —CHCH₃,—COOH, —CO₂(CH₂)_(m)CH₃, —OH, —CH₂OH, ethylene glycol, hexa(ethyleneglycol), —O(CH₂)_(m)CH₃, —NH₂, —NH(CH₂)_(m)NH₂, halogen, glucose,maltose, fullerene C60, a nucleic acid, a protein, or a ligand; and m is0-30.
 5. The method of claim 4, wherein the deposition compound isselected from the group consisting of 2-mercaptoacetic acid andn-octadecanethiol.
 6. The method of claim 1, wherein the substrate issilicon dioxide and the deposition compound is selected from the groupconsisting of a protein, a peptide and a compound having the formulaR₁SH or R₁SiCl₃, wherein: R₁ has the formula X(CH₂)_(n); n is 0-30; X is—CH₃, —CHCH₃, —COOH, —CO₂(CH₂)_(m)CH₃, —OH, —CH₂OH, ethylene glycol,hexa(ethylene glycol), —O(CH₂)_(m)CH₃, —NH₂, —NH(CH₂)_(m)NH₂, halogen,glucose, maltose, fullerene C60, a nucleic acid, a protein, or a ligand;and m is 0-30.
 7. The method of claim 6, wherein the deposition compoundis 16-mercapto-1-hexadecanoic acid, octadecyltrichlorosilane or3-(2-aminoethylamino)propyltrimethoxysllane.
 8. The method of claim 1,wherein the substrate is oxidized gallium arsenide or silicon dioxideand the deposition compound is a silazane.
 9. The method of claim 1,wherein said external opening comprises an internal diameter of about 1nanometer to about 15 nanometers.
 10. The method of claim 1, whereinmovement of said deposition compound is achieved by said driving force.11. The method of claim 1, wherein said tip is an atomic forcemicroscope tip.
 12. The method of claim 1, wherein said tip is a nearfield scanning optical microscope tip.
 13. The method of claim 1,wherein said tip is coated with a hydrophobic compound.
 14. The methodof claim 13, wherein the hydrophobic compound has the formula RNH₂wherein: R is an alkyl of the formula CH₃(CH₂)_(n) or an aryl; and n is0-30.
 15. The method of claim 14, wherein the hydrophobic compound is1-dodecylamine.
 16. A method of nanolithography, comprising: providing asubstrate; providing a scanning probe microscope tip comprising aninternal cavity having an external opening to the surface of said tip,wherein said tip is coated with a hydrophobic compound and wherein saidopening comprises an internal diameter of about 1 nanometer to about 15nanometers; loading said cavity with a deposition compound, wherein saiddeposition compound does not pass through said external opening in theabsence of a driving force; and subjecting said tip to a driving forceto deliver said deposition compound through said external opening to bedeposited on said substrate; wherein said driving force is selected fromthe group consisting of and electrical and a magnetic driving force,wherein, for the electrical driving force, the deposition compound is acharged compound subjected to an applied electric field, and wherein,for the magnetic driving force, the deposition compound is a magneticcompound or a magnetically tagged compound subjected to a magneticfield.
 17. A method of nanolithography, comprising: providing asubstrate; providing a scanning probe microscope tip; coating the tipwith a deposition compound; and subjecting said coated tip to a drivingforce to deliver said deposition compound to said substrate so as toproduce a desired pattern; wherein the driving force is selected fromthe group consisting of an electrical and a magnetic driving force,wherein, for the electrical driving force, the deposition compound is acharged biomolecule subjected to an applied electric field, and wherein,for the magnetic driving force, the deposition compound is a magneticcompound or a magnetically tagged compound subjected to a magneticfield.